A mudflap is something that hangs underneath but directly behind the wheels of any land vechicle. Mudflaps are used so that mud doesn't fling up while the wheels are spinning in rocks, dirt and of course, mud.

a description of the sagging labia minora. When a woman's inner pussy lips hang or protrude outside of a woman's pussy resembling a trucker's mudflaps. Often associated with age or child birth. Loathed by young men, savored by older men. Cursed by all women and often the leading reason for designer vaginal rejuvination.

Ewe, Dad, did you see the mudflaps on that old stripper? Yeah, Son I did. Mudflaps are great to suck on.